C++ 基于Qt示例从QThread下载Qt文件';行不通
嗨,我构建了一个简单的示例,将所有不相关的代码分条,只剩下有问题的代码 一般来说,我有一个执行线程的应用程序,在这个线程工作程序中,我放置了下载代码,该代码应该下载30多个文件,这是基于Qt给出的下载示例,问题是QNetworkAccessManager插槽从不调用。C++ 基于Qt示例从QThread下载Qt文件';行不通,c++,qt,download,qthread,C++,Qt,Download,Qthread,嗨,我构建了一个简单的示例,将所有不相关的代码分条,只剩下有问题的代码 一般来说,我有一个执行线程的应用程序,在这个线程工作程序中,我放置了下载代码,该代码应该下载30多个文件,这是基于Qt给出的下载示例,问题是QNetworkAccessManager插槽从不调用。 你能告诉我我做错了什么吗 class MainWindowContainer : public QMainWindow { Q_OBJECT public: MainWindowContainer(QWidge
你能告诉我我做错了什么吗
class MainWindowContainer : public QMainWindow
{
Q_OBJECT
public:
MainWindowContainer(QWidget *parent = 0);
public slots:
void InvokeDownloadThread();
private:
QPushButton *pushButtonInvokeThread;
PhotosDownloadWorker* pm_hotosDownloadWorker;
};
#include <QtGui>
#include "MainWindowContainer.h"
MainWindowContainer::MainWindowContainer(QWidget* parent) :
QMainWindow(parent)
{
pushButtonInvokeThread = new QPushButton(this);
QHBoxLayout *layout = new QHBoxLayout;
layout->addWidget(pushButtonInvokeThread);
setLayout(layout);
QObject::connect(pushButtonInvokeThread,SIGNAL(clicked()),this, SLOT(InvokeDownloadThread()));
}
void MainWindowContainer::InvokeDownloadThread()
{
pm_hotosDownloadWorker = new PhotosDownloadWorker(this);
pm_hotosDownloadWorker->Execute();
}
class PhotosDownloadWorker : public QThread
{
Q_OBJECT
public :
PhotosDownloadWorker(QObject *parent);
~PhotosDownloadWorker();
void Execute();
void append(const QStringList &urlList);
bool saveToDisk(const QString &filename, QIODevice *data);
QString saveFileName(const QUrl &url);
protected:
void run();
private:
bool m_abort;
QList<QNetworkReply *> currentDownloads;
QFile output;
QNetworkAccessManager* networkMgr ;
public slots:
void downloadFinished(QNetworkReply *reply);
void startNextDownload(const QUrl &url);
};
#include "PhotosDownloadWorker.h"
PhotosDownloadWorker::PhotosDownloadWorker(QObject *parent)
: QThread(parent)
{
m_abort = false;
networkMgr = new QNetworkAccessManager(this);
connect(networkMgr, SIGNAL(finished(QNetworkReply*)), this, SLOT(downloadFinished(QNetworkReply*)));
}
PhotosDownloadWorker::~PhotosDownloadWorker()
{
m_abort = true;
wait();
}
void PhotosDownloadWorker::Execute()
{
m_abort = false;
start();
}
void PhotosDownloadWorker::run()
{
QStringList m_urlList;
m_urlList.append("http://....xxxx......jpg");
m_urlList.append("http://....xxxx......jpg");
m_urlList.append("http://....xxxx......jpg");
m_urlList.append("http://....xxxx......jpg");
m_urlList.append("http://....xxxx......jpg");
m_urlList.append("http://....xxxx......jpg");
m_urlList.append("http://....xxxx......jpg");
m_urlList.append("http://....xxxx......jpg");
m_urlList.append("http://....xxxx......jpg");
m_urlList.append("http://....xxxx......jpg");
m_urlList.append("http://....xxxx......jpg");
m_urlList.append("http://....xxxx......jpg");
m_urlList.append("http://....xxxx......jpg");
// x 30
append(m_urlList);
}
void PhotosDownloadWorker::append(const QStringList &urlList)
{
foreach (QString url, urlList)
{
startNextDownload(QUrl::fromEncoded(url.toLocal8Bit()));
}
}
void PhotosDownloadWorker::startNextDownload(const QUrl &url)
{
QNetworkRequest request(url);
QNetworkReply *reply = networkMgr->get(request);
currentDownloads.append(reply);
}
bool PhotosDownloadWorker::saveToDisk(const QString &filename, QIODevice *data)
{
QFile file(filename);
if (!file.open(QIODevice::WriteOnly)) {
fprintf(stderr, "Could not open %s for writing: %s\n",
qPrintable(filename),
qPrintable(file.errorString()));
return false;
}
file.write(data->readAll());
file.close();
return true;
}
void PhotosDownloadWorker::downloadFinished(QNetworkReply *reply)
{
QUrl url = reply->url();
if (reply->error()) {
fprintf(stderr, "Download of %s failed: %s\n",
url.toEncoded().constData(),
qPrintable(reply->errorString()));
} else {
QString filename = saveFileName(url);
if (saveToDisk(filename, reply))
printf("Download of %s succeeded (saved to %s)\n",
url.toEncoded().constData(), qPrintable(filename));
}
reply->deleteLater();
currentDownloads.removeAll(reply);
if (currentDownloads.isEmpty())
{
this->exit();
}
}
QString PhotosDownloadWorker::saveFileName(const QUrl &url)
{
QString path = url.path();
QString basename = QFileInfo(path).fileName();
if (basename.isEmpty())
basename = "download";
if (QFile::exists(basename)) {
// already exists, don't overwrite
int i = 0;
basename += '.';
while (QFile::exists(basename + QString::number(i)))
++i;
basename += QString::number(i);
}
return basename;
}
//main
#include "MainWindowContainer.h"
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
MainWindowContainer mainWindowContainer;
mainWindowContainer.show();
return app.exec();
}
class MainWindowContainer:公共QMainWindow
{
Q_对象
公众:
MainWindowContainer(QWidget*parent=0);
公众时段:
void InvokeDownloadThread();
私人:
QPushButton*pushButtonInvokeThread;
PhotosDownloadWorker*pm_hotosDownloadWorker;
};
#包括
#包括“MainWindowContainer.h”
MainWindowContainer::MainWindowContainer(QWidget*父项):
QMainWindow(父窗口)
{
pushButtonInvokeThread=新的QPushButton(此);
QHBoxLayout*布局=新的QHBoxLayout;
布局->添加小部件(pushButtonInvokeThread);
设置布局(布局);
连接(pushButtonInvokeThread,SIGNAL(clicked()),this,SLOT(InvokeDownloadThread());
}
void MainWindowContainer::InvokeDownloadThread()
{
pm_hotosDownloadWorker=新的PhotosDownloadWorker(此);
pm_hotosDownloadWorker->Execute();
}
类PhotoDownloadWorker:publicQThread
{
Q_对象
公众:
PhotoDownloadWorker(QObject*父对象);
~photodownloadworker();
void Execute();
void append(const-QStringList和urlist);
bool saveToDisk(常量QString和文件名,QIODevice*数据);
QString保存文件名(const-QUrl&url);
受保护的:
无效运行();
私人:
布尔穆尔流产;
QList当前下载;
QFile输出;
QNetworkAccessManager*networkMgr;
公众时段:
无效下载完成(QNetworkReply*reply);
void startNextDownload(const-QUrl和url);
};
#包括“PhotoDownloadWorker.h”
PhotoDownloadWorker::PhotoDownloadWorker(QObject*父对象)
:QThread(父线程)
{
m_abort=false;
networkMgr=新的QNetworkAccessManager(此);
连接(networkMgr,信号(完成(QNetworkReply*)),此,插槽(下载完成(QNetworkReply*));
}
PhotoDownloadWorker::~PhotoDownloadWorker()
{
m_abort=true;
等待();
}
void photodownloadWorker::Execute()
{
m_abort=false;
start();
}
void photodownloadWorker::run()
{
QStringList m_urlist;
m_urlist.append(“http://....xxxx......jpg");
m_urlist.append(“http://....xxxx......jpg");
m_urlist.append(“http://....xxxx......jpg");
m_urlist.append(“http://....xxxx......jpg");
m_urlist.append(“http://....xxxx......jpg");
m_urlist.append(“http://....xxxx......jpg");
m_urlist.append(“http://....xxxx......jpg");
m_urlist.append(“http://....xxxx......jpg");
m_urlist.append(“http://....xxxx......jpg");
m_urlist.append(“http://....xxxx......jpg");
m_urlist.append(“http://....xxxx......jpg");
m_urlist.append(“http://....xxxx......jpg");
m_urlist.append(“http://....xxxx......jpg");
//x30
附加(m_urlist);
}
void photodownloadWorker::append(常量QStringList&urlist)
{
foreach(qstringurl,urlist)
{
startNextDownload(QUrl::fromcoded(url.toLocal8Bit());
}
}
void photodownloadWorker::startNextDownload(const-QUrl&url)
{
QNetworkRequest请求(url);
QNetworkReply*reply=networkMgr->get(请求);
currentDownloads.append(回复);
}
bool photodownloadWorker::saveToDisk(常量QString和文件名,QIODevice*数据)
{
QFile文件(文件名);
如果(!file.open(QIODevice::WriteOnly)){
fprintf(stderr,“无法打开%s进行写入:%s\n”,
qPrintable(文件名),
qPrintable(file.errorString());
返回false;
}
write(data->readAll());
file.close();
返回true;
}
void PhotosDownloadWorker::downloadFinished(QNetworkReply*reply)
{
QUrl url=回复->url();
如果(回复->错误()){
fprintf(标准,“下载%s失败:%s\n”,
url.toEncoded().constData(),
qPrintable(回复->错误字符串());
}否则{
QString文件名=保存文件名(url);
if(saveToDisk(文件名,回复))
printf(“下载%s成功(保存到%s)\n”,
url.toEncoded().constData(),qPrintable(文件名));
}
回复->删除稍后();
currentDownloads.removeAll(回复);
if(currentDownloads.isEmpty())
{
此->退出();
}
}
QString photodownloadWorker::saveFileName(const-QUrl&url)
{
QString path=url.path();
QString basename=QFileInfo(path).fileName();
if(basename.isEmpty())
basename=“下载”;
如果(QFile::exists(basename)){
//已存在,请不要覆盖
int i=0;
basename+='.';
而(QFile::exists(basename+QString::number(i)))
++一,;
basename+=QString::number(i);
}
返回basename;
}
//主要
#包括“MainWindowContainer.h”
int main(int argc,char*argv[])
{
QApplication应用程序(argc、argv);
MainWindowContainer MainWindowContainer;
mainWindowContainer.show();
返回app.exec();
}
我认为如果参数列表不匹配,它甚至不会将信号连接到插槽。有关运行时的警告,请参见调试器输出(“应用程序输出”选项卡)
因此,与其
connect(networkMgr, SIGNAL(readyRead()), this, SLOT(downloadFinished(QNetworkReply*)));
做
处理错误是通过QNetworkReply的。在get
之后,您就可以连接到信号。尽管您在代码中调用了“networkMgr->get(request)”,但您的线程可能在实际下载开始之前退出。尝试将“exec()”调用放在“QThread::run()”方法的最底部,以在线程中输入QNetworkAccessManager工作所需的事件循环。这也会防止线程过早地完成其执行。您的代码如下所示:
void PhotosDownloadWorker::run()
{
QStringList m_urlList;
m_urlList.append("http://....xxxx......jpg");
m_urlList.append("http://....xxxx......jpg");
// x 30
append(m_urlList);
exec();
}
W
void PhotosDownloadWorker::run()
{
QStringList m_urlList;
m_urlList.append("http://....xxxx......jpg");
m_urlList.append("http://....xxxx......jpg");
// x 30
append(m_urlList);
exec();
}